In communications networks, there may be a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the communications network is deployed.
One component of wireless communications networks where it may be challenging to obtain good performance and capacity is the antennas of network nodes configured for wireless communications; either to/from another network node, and/or to/from a wireless user terminal.
For example, massive beamforming, i.e., beamforming using active antenna arrays with orders of magnitudes more antenna elements than used in current communications networks, is expected to become a technical component in the radio access part of future fifth generation (5G) communications networks. By using large antenna arrays at the radio base stations, user data can be transmitted focused in space so that energy is received mainly by the wireless device dedicated by the user data, thus resulting in little interference being perceived by other wireless devices or other types of nodes. Massive beamforming has therefore the potential to increase system capacity and energy efficiency by orders of magnitudes.
As carrier frequency increases it is foreseen that the number of radio chains in the active antenna arrays can be comparatively large, possibly several hundreds. This type of large antenna arrays is suitable for analog beamforming networks since it does not need any attenuators. This type of large antenna arrays is also suitable for user specific beamforming by creating narrow transmission beams in directions where the radio channel is strong towards a user. However, when signals are to be transmitted over a larger area, for example control plane transmission, the antenna arrays are not that suitable if conventional techniques are used to form the wider transmission beams. The conventional technique is to apply amplitude taper which results in many power amplifiers in the radio chains being more or less not used and, as a consequence, the total output power is reduced.
Hence, there is still a need for improved beamforming mechanisms.